This invention relates to a multicolor heat-sensitive recording apparatus which produces multicolor recording according to a thermal transfer recording system, and more particularly to a multi-color heat-sensitive recording apparatus which, in carrying out the recording operation, allows a recording sheet to pass through only such recording sections as are necessary for a given recording operation.
FIG. 1 illustrates the principle of a thermal transfer type heat-sensitive recording apparatus. In this apparatus, an ink donor sheet 4 and a recording sheet 3 placed thereon run between a heat-sensitive recording head 1 and a pressure roll 2. The ink donor sheet 4 is provided with a support paper 4A which is coated with thermally melting or sublimating solid ink 4B. Therefore, by selectively heating the heat generating resistors 1A of the heat-sensitive recording head 1 according to image data, molten or sublimated ink may be transferred onto the recording sheet 3; that is, the image data are recorded on the sheet.
FIG. 2 depicts a conventional multi-color heat-sensitive recording apparatus operating according to the above-described principle. The apparatus has a sheet conveying path 6 along which a recording sheet 3 is run. First, second and third recording sections 7, 8 and 9 are arranged along the sheet conveying path 3 in the stated order. In the first printing section 7, red color printing is carried out.
The first printing section 7 is provided with a pressure roll 11 provided on one side of the sheet conveying path 6, a thermal head 12 which confronts the pressure roll 11, a supply roll 13, a winding roll which drives or conveys an ink donor sheet 14, which is supplied by the supply roll 13, between the pressure roll 11 and the thermal head 12 and then takes it up, and guides 16 and 17 arranged in the ink donor sheet running system. In the second recording section 8, printing in yellow is carried out. Similarly as in the first recording section 7, the second recording section 8 is provided with a pressure roll 21, a thermal head 22, a supply roll 23 for supplying an ink donor sheet 24, a winding roll 25 and guides 26 and 27. In the third recording section 9, printing in blue is carried out. Similarly, the third recording section 9 is provided with a pressure roll 31, a thermal head 32, a supply roll 33 for supplying an ink donor sheet 34, a winding roll 35 and guides 36 and 37. A pair of conveying rolls 41 and 42 are provided near the start point of the sheet conveying path 6, to convey the recording sheet 3 to the first recording section 7. A pair of discharging rolls 43 and 44 are provided near the end point of the sheet conveying path 6, to deliver the recorded sheet 3 to a discharge tray (not shown).
When the multi-color heat-sensitive recording apparatus thus constructed begins recording, first the recording sheet 3 is delivered to the first recording section 7 by the conveying rolls 41 and 42. Solid, red ink for data recording has been applied to the ink donor sheet 14 in the first recording section 7, and therefore, red image data are recorded on the recording sheet 3 as it passes the thermal head 12. The recording sheet 3 is then forwarded to the second recording section 8 by rotation, in the direction of the arrow, of the pressure roll 11 and by the conveyance, in the direction of the arrow, of the ink donor web 14. Solid, yellow ink for data recording has been applied to the ink donor sheet 24 in the second recording section 8. Therefore, yellow image data are recorded on the sheet. Similarly as in the above-described case, the recording sheet 3 is delivered to the third recording section 9, where blue image data are recorded on the sheet by the ink donor sheet 34 which has been coated with solid, blue ink. As the pressure roll 31 rotates while the ink donor sheet 34 is transported, the recording sheet 3 on which the three color image has been recorded is delivered to the discharging rolls 43 and 44 and is then sent to the discharge tray.
As was described above, in the conventional multi-color heat-sensitive recording apparatus, the recording sheet is conveyed along a single sheet conveying path. Therefore, even when the operation of only one of the recording sections is required, as in the case of monochromatic printing, the ink donor sheets in all of the recording sections must be conveyed because it is necessary to convey the recording sheet to the discharge tray. Therefore, the ink donor sheets are consumed uneconomically. In this point, the conventional apparatus is disadvantageous.